Forschungsberichte aus der Industriellen Informationstechnik 15 Damián Ezequiel Alonso Wireless Data Transmission for the Battery Management System of Electric and Hybrid Vehicles Wireless Data Transmission for BatteryWireless Data Transmission Management Systems Damián EzequielDamián Alonso Damián Ezequiel Alonso Wireless Data Transmission for the Battery Management System of Electric and Hybrid Vehicles Forschungsberichte aus der Industriellen Informationstechnik Band 15 Institut für Industrielle Informationstechnik Karlsruher Institut für Technologie Hrsg. Prof. Dr.-Ing. Fernando Puente León Prof. Dr.-Ing. habil. Klaus Dostert Eine Übersicht aller bisher in dieser Schriftenreihe erschienenen Bände finden Sie am Ende des Buchs. Wireless Data Transmission for the Battery Management System of Electric and Hybrid Vehicles by Damián Ezequiel Alonso Karlsruher Institut für Technologie Institut für Industrielle Informationstechnik Wireless Data Transmission for the Battery Management System of Electric and Hybrid Vehicles Zur Erlangung des akademischen Grades eines Doktor-Ingenieurs von der Fakultät für Elektrotechnik und Informationstechnik des Karlsruher Instituts für Technologie (KIT) genehmigte Dissertation von Ing. Damián Ezequiel Alonso aus Buenos Aires, Argentinien Tag der mündlichen Prüfung: 08. August 2016 Referenten: Prof. Dr.-Ing. habil. Klaus Dostert Prof. Dr.-Ing. Thomas Zwick Impressum Karlsruher Institut für Technologie (KIT) KIT Scientific Publishing Straße am Forum 2 D-76131 Karlsruhe KIT Scientific Publishing is a registered trademark of Karlsruhe Institute of Technology. Reprint using the book cover is not allowed. www.ksp.kit.edu This document – excluding the cover, pictures and graphs – is licensed under a Creative Commons Attribution-Share Alike 4.0 International License (CC BY-SA 4.0): https://creativecommons.org/licenses/by-sa/4.0/deed.en The cover page is licensed under a Creative Commons Attribution-No Derivatives 4.0 International License (CC BY-ND 4.0): https://creativecommons.org/licenses/by-nd/4.0/deed.en Print on Demand 2017 – Gedruckt auf FSC-zertifiziertem Papier ISSN 2190-6629 ISBN 978-3-7315-0670-6 DOI 10.5445/KSP/1000069560 Abstract Battery management systems (BMSs) are designed to monitor and control the traction battery in hybrid and electric vehicles. A communication net- work is established within the battery, in order to collect the information measured by sensors distributed among the battery cells. State-of-the-art BMSs employ wired bus systems, such as the CAN bus. This leads to the installation of large wiring harnesses, which increases costs and manu- facturing complexity. This thesis introduces a novel wireless approach for the data transmission within the BMS, which consists of installing an antenna in each communication device of the BMS. Two antenna types operating in two different frequency ranges have been chosen as candidates. The investigation of the wireless in-battery channel is first realized by means of measurements in self-designed chan- nel emulators, and then expanded by means of software-based electro- magnetic simulations. The influence of different system parameters on the channel is analyzed, such as physical dimensions, and number and position of the antennas. A simple architecture for the communication modems is proposed. The entire communication system is first simulated in software and then implemented by means of rapid prototyping platforms. The performance is measured in the channel emulator and also in a real automotive battery. The results of channel measurements and simulations, as well as the communication system performance, confirm the technical feasibility of the wireless data transmission for the BMS. The necessary transmission power is very low in every considered case. Working at low frequencies is a good alternative for a reduced number of antennas, due to the lower de- pendence of the studied system parameters on the channel characteristics. However, operating at higher frequencies is a better approach for larger numbers of antennas: The transmission power is lower and the suggested type of antenna is smaller and cheaper. Zusammenfassung Batteriemanagementsysteme (BMS) werden für die Überwachung und Steuerung der Traktionsbatterien in Hybrid- und Elektrofahrzeugen ent- worfen. Ein Kommunikationsnetzwerk wird in die Batterie eingesetzt, um die Informationen zu sammeln, die von Sensoren zwischen den Bat- teriezellen gemessen werden. Aktuelle BMS verwenden verdrahtete Bussysteme wie CAN-Bus. Dies führt zur Installation von großen Kabel- bäumen, was die Kosten und den Herstellungsaufwand erhöht. In dieser Arbeit wird ein neuartiger drahtloser Ansatz für die Datenübertragung in- nerhalb des BMS dargestellt, der die Installation einer Antenne bei jedem Kommunikationsgerät des BMS vorsieht. Zwei Antennenarten für zwei verschiedene Frequenzbereiche wurden als Kandidaten ausgewählt. Die Untersuchung des drahtlosen in-Batterie- Kanals wird zuerst durch Messungen in selbstentworfenen Kanalemula- toren durchgeführt und danach mittels softwarebasierten elektromagnetis- chen Simulationen erweitert. Der Einfluss verschiedener Systemparame- ter auf den Kanal wird untersucht , z. B. die physikalischen Dimensionen und die Anzahl und Position der Antennen. Eine einfache Architektur wird für die Modems des Kommunikation- ssystems vorgeschlagen. Das gesamte Kommunikationssystem wird zuerst in einer Software simuliert und anschließend mittels Rapid-Proto- typing-Plattformen implementiert. Die Leistung wird im Kanalemulator sowie auch in einer realen Fahrzeugbatterie gemessen. Die Ergebnisse der Kanalmessungen und Simulationen sowie die Leis- tung des Systems bestätigen die technische Machbarkeit der drahtlosen Datenübertragung für das BMS. Die notwendige Sendeleistung ist sehr gering in jedem betrachteten Fall. Aufgrund der geringen Abhängigkeit der Kanaleigenschaften von den untersuchten Systemparametern ist das Arbeiten bei niedrigen Frequenzen eine gute Alternative für eine re- duzierte Anzahl von Antennen. Aufgrund der wesentlich niedrigeren erforderlichen Sendeleistung sowie billigeren und kleinern Antennen sind höhere Frequenzen für große Antennenzahlen ein besserer Ansatz. Acknowledgements “We are like dwarves perched on the shoulders of giants” (Bernard of Chartres) First of all, I would like to sincerely thank my supervisor Prof. Dr.-Ing. habil. Klaus Dostert for the opportunity to carry out my PhD thesis at the Karslruhe Institute of Technology (KIT), as well as his continuous and valuable support to my work. I would also like to acknowledge Prof. Dr.-Ing. Thomas Zwick for the co-supervision of my work and his relevant advice to improve my thesis. I am deeply grateful to all my colleagues and the personal staff at the Institute of Industrial Information (IIIT) for the friendly working atmosphere, as well as the good advice and cooperation. I would really like to particularly thank my colleague Oliver Opalko for his valuable collaboration within the IntLiIon project, his dedication to revise my thesis, and for being an awesome office mate. I have to pleasure the cooperation of the partners from Bosch, ProDe- sing and the Hochschule Hannover along the IntLiIon project. I specially owe gratitude to Thomas Buck and Wenqing Liu for giving me access to the Bosch Battery Labs, where I could demonstrate the conclusions of my investigation in a real automotive battery. I am grateful to my students, who contributed to my research with their theses or working as HiWis. It has been a pleasure to work together. I want also to thank all the wonderful friends that I met during these years in Karlsruhe and made me really enjoy my time in this city. Finally but most important, I want to express my infinite gratitude to my parents and my sister. Every step forward in my life, does not matter how big or small it is, is thank to the values learned at home, as well as their continuous support and love despite the long distance. Contents Abstract .................................i Zusammenfassung ........................... iii Acknowledgements ...........................v Nomenclature .............................. xi 1 Introduction ..............................1 1.1 Motivation............................ 1 1.2 In-Battery Communication................... 3 1.2.1 State of the Art and Problem Statement........ 3 1.3 The Wireless Approach..................... 4 1.3.1 Framework of the Project................. 4 1.3.2 Goals and Challenges................... 4 1.3.3 Scope of the Work..................... 6 1.4 Project Specifications and Requirements........... 7 1.5 Related Work........................... 8 1.6 Structure of the Thesis...................... 9 2 Measurement Testbed of the Wireless In-Battery Channel ... 11 2.1 Wireless In-Battery Channel Emulator............ 11 2.2 Comparison With Ideal Cavity Resonators.......... 13 2.3 Antenna Connection and Orientation............. 14 2.4 Setup for CTF Measurements.................. 16 3 Channel Measurements and Selection of the Antennas .... 17 3.1 Investigated Frequency Range................. 17 3.2 Investigated Antenna Types.................. 19 3.3 Evaluated Antennas....................... 21 3.4 Pre-Selection of the Antennas................. 23 3.4.1 Performance Comparison by means of the CTF.... 23 3.4.2 Comparison Procedure.................. 25 3.4.3 CTF Measurements in the Small Channel Emulator. 25 viii Contents 3.4.4 Pre-Selected Antennas.................. 29 3.4.5 CTF Measurements in the Big Channel Emulator... 31 3.5 Manufacturing